ThoughtFox
Expecting the Unexpected
IMHO, when you have a small house like that, and 3 toddlers who aren't related to each other and their various parents and a grandma all living there, you DON'T go checking on a toddler in the middle of the night to see if they're okay. You're grateful for every bit of peace you can find.
I personally didn't ever check on my 20 month old babies unless they cried during the night or I heard something alarming. If they were healthy, and sleeping, I let them be.
I agree - my kids mostly slept through the night, but I let them stay up later in the evening, and usually we were worn out before they settled down. I always dreamed of putting a toddler down at 8 p.m. but it usually didn't happen, LOL.
And sometimes they would sleep 8-10 hours, but it was never like clockwork. Teething can interfere with sleep, or a dirty diaper, or with a younger baby, simply hunger.
I'm surprised no one has mentioned whether they fixed her a bottle that night before bedtime. With a sling on her arm, could she hold a bottle? If not, she probably would have whined or cried. I just wish we knew more about her regular routine.